Abstract : The detachment of gelatinous layer G-layer, often observed on microtome cross sections, leads some authors believe that G-layer cannot act as the driving force of longitudinal shrinkage in tension wood. The aim of this study was to observe the detachment of G-layer along fibres. Green wood block was cut transversely into two samples. One sample was kept in water and the other oven-dried. One face being common to both samples, detachment of G-layer has been studied on the same fibres. Observations have been performed after blocking deformation by embedding. It reveals that the detachment of G-layer is a cutting effect produced during the first making of the transverse face of the wood block to be embedded. After 100 µm far from this primary surface of the sample no detachment can be observed. Drying shrinkage does not affect or little this detachment. The result seems to explain well why the detachment of G-layer occurs during sectioning using a conventional sliding microtomy. These observations prove the adhesion of G-layer in massive wood and confirm the active role of G-layer in tension wood properties.